Images captured via a camera are subject to blurriness introduced through unintentional vibration of the camera body, elements within the camera or elements within the camera lens. Photographers and videographers have employed tripods or other stable supports to ensure sharper images. However, it is often the case that a stable tripod or other support for the camera is unavailable. Consequently, photographers and videographers often use still and video cameras that employ image stabilization techniques.
Image stabilized lenses and cameras use small gyroscopes or other sensors and mechanical systems to counteract camera or lens motion to obtain sharper images. Image stabilizers produce sharper images by counteracting measured motion. Signals, generated by the gyroscopes, are sent to a servo motor, which moves lens elements, a prism, or a sensor plane in the opposite direction of camera or lens motion. Larger gyroscopic stabilizers can steady an entire camera body and lens assembly, whether the lens assembly is optically stabilized or not.
An optical image stabilizer, often abbreviated as OIS, is a mechanism used in a still camera or video camera that stabilizes the recorded image by varying the optical path to the sensor. This technology is implemented in the lens itself, rather than in the camera or via a tripod mount. An OIS reduces the size and weight of the camera assembly and enables the lens assembly to be fine-tuned to match characteristics of that particular lens assembly and adjust for present environmental conditions. Vibration signals are generally acquired using two piezoelectric sensors. The sensors react to angular velocity. One of the sensors detects horizontal movement. The other sensor detects vertical movement. As a result, an OIS corrects for pitch and yaw axis rotations only. No correction is possible for rotation about the optical axis.
Digital image stabilization is used in some video cameras. This image stabilization technique moves the electronic image from frame to frame to counteract motion. Generally, pixels outside of the border of the visible frame are captured and available to shift the visible frame as may be required to buffer motion between frames.
Some image processing systems use stabilization filters that can correct a blurry image by tracking the movement of pixels in the image and correcting the image. The process is similar to digital image stabilization. However, these image processing systems often use image information from the image sensor to determine when image information has moved. Such systems typically use multiple exposures with dedicated frame buffers for each exposure and a competent processor to perform correlation calculations to sense relative motion between subexposures, leading to a significant increase in unit cost. In addition, systems that use stabilization filters often extrapolate image information in an attempt to recreate lost image information at the edge of a frame.
As cameras become smaller and sensor resolutions increase, captured images will become more sensitive to mechanical disturbances during exposure. For cameras with a wide field of view, such as cameras integrated in mobile phones, rotation about the optical axis is a significant obstacle to the acquisition of high-quality images. Mechanical disturbances between the camera and the subject or within the camera in yaw and pitch directions will continue to be important to the acquisition of high-quality images.
Therefore, it would be desirable to provide a low cost, reliable and integrated image stabilization solution that can perform across a range of image capture devices and environmental conditions.